如何在 shapefile (sf) 列表中设置 crs？
How to set the crs on a list of shapefiles (sf)?
我正在读取 shapefile 列表（如 sf），我想设置 crs。我知道这可以很容易地为一个 shapefile 完成（例如，），但我还没有找到针对多个或一系列 shapefile 的解决方案。
我正在阅读 list.files 和 lapply 的 shapefile。
library(sf)
# Example (Not Run)
temp = list.files(path = "/data",
pattern = "*WEST.shp$",
full.names = TRUE)
# Then, apply the st_read function to the list of shapefiles (Not Run).
myfiles = lapply(temp, st_read)
如果读入 1 个 shapefile，那么您只需通过以下方式设置 crs：
boundary <- st_read(
"/data/tsugWEST.shp", crs = 4326)
但是，如果我用 lapply 来做，那么 returns 会出现以下错误：
Error in st_read.default(crs = 4326): dsn should specify a data
source or filename
示例数据（即读入 R 后的 shapefile 列表）
shapefiles <- list(abieWEST.shp = structure(list(AREA = 1, PERIMETER = 0, ABIELASI_ = 0,
ABIELASI_I = 0, CODE = 0L, geometry = structure(list(structure(list(
structure(c(-126.623274277836, -122.269490649612, -117.311014850802,
-114.529430866103, -113.803800261399, -112.836292788461,
-108.603447594355, -103.765910229662, -102.193710586137,
-101.105264679081, -101.58901841555, -107.515001687299,
-115.255061470807, -117.552891719036, -125.897643673132,
-130.49330416959, -141.740578542501, -146.940931209546,
-144.643100961316, -136.056472138987, -126.623274277836,
63.8736898397207, 61.9386748938436, 55.5289378856255,
55.4079994515082, 54.0776766762177, 52.9892307691618,
48.9982624432902, 45.3701094197706, 42.8304023033068,
36.7834805974407, 28.3177902092282, 23.8430681468874,
24.3268218833566, 27.834036472759, 35.5740962562675,
49.2401393115248, 55.6498763197429, 63.1480592350168,
65.4458894832459, 65.4458894832459, 63.8736898397207), .Dim = c(21L,
2L))), class = c("XY", "POLYGON", "sfg"))), n_empty = 0L, crs = structure(list(
input = NA_character_, wkt = NA_character_), class = "crs"), class = c("sfc_POLYGON",
"sfc"), precision = 0, bbox = structure(c(xmin = -146.940931209546,
ymin = 23.8430681468874, xmax = -101.105264679081, ymax = 65.4458894832459
), class = "bbox"))), row.names = c(NA, -1L), class = c("sf",
"data.frame"), sf_column = "geometry", agr = structure(c(AREA = NA_integer_,
PERIMETER = NA_integer_, ABIELASI_ = NA_integer_, ABIELASI_I = NA_integer_,
CODE = NA_integer_), class = "factor", .Label = c("constant",
"aggregate", "identity"))), acerWEST.shp = structure(list(AREA = 1,
PERIMETER = 0, ABIELASI_ = 0, ABIELASI_I = 0, CODE = 0L,
geometry = structure(list(structure(list(structure(c(-108.146180374448,
-125.155521463775, -140.514702596675, -134.929545821075,
-128.963582901684, -126.805681420203, -124.647779938721,
-123.886167651139, -120.458912357021, -120.458912357021,
-114.746820200157, -111.573435668566, -108.526986518239,
-107.003761943076, -107.003761943076, -104.591989699066,
-104.084248174012, -102.561023598848, -104.845860461594,
-102.053282073794, -98.1182852546211, -94.310223816712, -108.146180374448,
15.5862714176048, 37.6730277574772, 57.9826887596588, 60.013654859877,
55.9517226594406, 56.9672057095497, 55.5709165156497, 55.6978518969134,
56.0786580407043, 54.3015627030134, 51.2551135526862, 47.827858258568,
47.9547936398317, 46.5585044459317, 45.416086014559, 42.2427014829681,
37.6730277574772, 37.1652862324227, 34.1188370820955, 30.3107756441864,
30.5646464067137, 26.2488434437501, 15.5862714176048), .Dim = c(23L,
2L))), class = c("XY", "POLYGON", "sfg"))), n_empty = 0L, crs = structure(list(
input = NA_character_, wkt = NA_character_), class = "crs"), class = c("sfc_POLYGON",
"sfc"), precision = 0, bbox = structure(c(xmin = -140.514702596675,
ymin = 15.5862714176048, xmax = -94.310223816712, ymax = 60.013654859877
), class = "bbox"))), row.names = c(NA, -1L), class = c("sf",
"data.frame"), sf_column = "geometry", agr = structure(c(AREA = NA_integer_,
PERIMETER = NA_integer_, ABIELASI_ = NA_integer_, ABIELASI_I = NA_integer_,
CODE = NA_integer_), class = "factor", .Label = c("constant",
"aggregate", "identity"))))
对于列表中的 1 个 shapefile，我可以通过以下操作轻松设置 crs：
st_crs(shapefiles[[1]]) <- 4326
如果我尝试使用此代码使用 lapply 或 purrr::map，则它不起作用。
lapply(myfiles, st_crs() <- 4326)
错误
Error in st_crs() <- 4326 : invalid (NULL) left side of assignment
我也尝试过以类似的方式使用 st_transform，但它也没有用。
我想做的是使用 st_crs(shapefiles[[1]]) <- 4326 之类的东西，但将其应用于列表中的每个元素（即 shapefile）。另外，我想避免使用 for 循环。我宁愿使用 apply 或 purrr 函数。
我们只需要 lapply 中的 lambda（匿名）函数来进行赋值，然后 return 原始对象
shapefiles2 <- lapply(shapefiles, function(x) {st_crs(x) <- 4326; x})
-输出
shapefiles2
$abieWEST.shp
Simple feature collection with 1 feature and 5 fields
Geometry type: POLYGON
Dimension: XY
Bounding box: xmin: -146.9409 ymin: 23.84307 xmax: -101.1053 ymax: 65.44589
Geodetic CRS: WGS 84
AREA PERIMETER ABIELASI_ ABIELASI_I CODE geometry
1 1 0 0 0 0 POLYGON ((-126.6233 63.8736...
$acerWEST.shp
Simple feature collection with 1 feature and 5 fields
Geometry type: POLYGON
Dimension: XY
Bounding box: xmin: -140.5147 ymin: 15.58627 xmax: -94.31022 ymax: 60.01365
Geodetic CRS: WGS 84
AREA PERIMETER ABIELASI_ ABIELASI_I CODE geometry
1 1 0 0 0 0 POLYGON ((-108.1462 15.5862...
或使用map
library(purrr)
map(shapefiles, ~ {
st_crs(.x) <- 4326
.x
})
另一种选择（如上面@Henrik 所建议的）是将 crs 作为 FUN 的可选参数（即 st_read）。
library(sf)
# Example (Not Run)
temp = list.files(path = "/data",
pattern = "*WEST.shp$",
full.names = TRUE)
myfiles = lapply(temp, st_read, crs = 4326)
输出
Reading layer `abieWEST' from data source
`/data/abieWEST.shp'
using driver `ESRI Shapefile'
Simple feature collection with 1 feature and 5 fields
Geometry type: POLYGON
Dimension: XY
Bounding box: xmin: -146.9409 ymin: 23.84307 xmax: -101.1053 ymax: 65.44589
Geodetic CRS: WGS 84
Reading layer `acerWEST' from data source
`/data/acerWEST.shp'
using driver `ESRI Shapefile'
Simple feature collection with 1 feature and 5 fields
Geometry type: POLYGON
Dimension: XY
Bounding box: xmin: -140.5147 ymin: 15.58627 xmax: -94.31022 ymax: 60.01365
Geodetic CRS: WGS 84
我正在读取 shapefile 列表（如 sf），我想设置 crs。我知道这可以很容易地为一个 shapefile 完成（例如，
我正在阅读 list.files 和 lapply 的 shapefile。
library(sf)
# Example (Not Run)
temp = list.files(path = "/data",
pattern = "*WEST.shp$",
full.names = TRUE)
# Then, apply the st_read function to the list of shapefiles (Not Run).
myfiles = lapply(temp, st_read)
如果读入 1 个 shapefile，那么您只需通过以下方式设置 crs：
boundary <- st_read(
"/data/tsugWEST.shp", crs = 4326)
但是，如果我用 lapply 来做，那么 returns 会出现以下错误：
Error in st_read.default(crs = 4326): dsn should specify a data source or filename
示例数据（即读入 R 后的 shapefile 列表）
shapefiles <- list(abieWEST.shp = structure(list(AREA = 1, PERIMETER = 0, ABIELASI_ = 0,
ABIELASI_I = 0, CODE = 0L, geometry = structure(list(structure(list(
structure(c(-126.623274277836, -122.269490649612, -117.311014850802,
-114.529430866103, -113.803800261399, -112.836292788461,
-108.603447594355, -103.765910229662, -102.193710586137,
-101.105264679081, -101.58901841555, -107.515001687299,
-115.255061470807, -117.552891719036, -125.897643673132,
-130.49330416959, -141.740578542501, -146.940931209546,
-144.643100961316, -136.056472138987, -126.623274277836,
63.8736898397207, 61.9386748938436, 55.5289378856255,
55.4079994515082, 54.0776766762177, 52.9892307691618,
48.9982624432902, 45.3701094197706, 42.8304023033068,
36.7834805974407, 28.3177902092282, 23.8430681468874,
24.3268218833566, 27.834036472759, 35.5740962562675,
49.2401393115248, 55.6498763197429, 63.1480592350168,
65.4458894832459, 65.4458894832459, 63.8736898397207), .Dim = c(21L,
2L))), class = c("XY", "POLYGON", "sfg"))), n_empty = 0L, crs = structure(list(
input = NA_character_, wkt = NA_character_), class = "crs"), class = c("sfc_POLYGON",
"sfc"), precision = 0, bbox = structure(c(xmin = -146.940931209546,
ymin = 23.8430681468874, xmax = -101.105264679081, ymax = 65.4458894832459
), class = "bbox"))), row.names = c(NA, -1L), class = c("sf",
"data.frame"), sf_column = "geometry", agr = structure(c(AREA = NA_integer_,
PERIMETER = NA_integer_, ABIELASI_ = NA_integer_, ABIELASI_I = NA_integer_,
CODE = NA_integer_), class = "factor", .Label = c("constant",
"aggregate", "identity"))), acerWEST.shp = structure(list(AREA = 1,
PERIMETER = 0, ABIELASI_ = 0, ABIELASI_I = 0, CODE = 0L,
geometry = structure(list(structure(list(structure(c(-108.146180374448,
-125.155521463775, -140.514702596675, -134.929545821075,
-128.963582901684, -126.805681420203, -124.647779938721,
-123.886167651139, -120.458912357021, -120.458912357021,
-114.746820200157, -111.573435668566, -108.526986518239,
-107.003761943076, -107.003761943076, -104.591989699066,
-104.084248174012, -102.561023598848, -104.845860461594,
-102.053282073794, -98.1182852546211, -94.310223816712, -108.146180374448,
15.5862714176048, 37.6730277574772, 57.9826887596588, 60.013654859877,
55.9517226594406, 56.9672057095497, 55.5709165156497, 55.6978518969134,
56.0786580407043, 54.3015627030134, 51.2551135526862, 47.827858258568,
47.9547936398317, 46.5585044459317, 45.416086014559, 42.2427014829681,
37.6730277574772, 37.1652862324227, 34.1188370820955, 30.3107756441864,
30.5646464067137, 26.2488434437501, 15.5862714176048), .Dim = c(23L,
2L))), class = c("XY", "POLYGON", "sfg"))), n_empty = 0L, crs = structure(list(
input = NA_character_, wkt = NA_character_), class = "crs"), class = c("sfc_POLYGON",
"sfc"), precision = 0, bbox = structure(c(xmin = -140.514702596675,
ymin = 15.5862714176048, xmax = -94.310223816712, ymax = 60.013654859877
), class = "bbox"))), row.names = c(NA, -1L), class = c("sf",
"data.frame"), sf_column = "geometry", agr = structure(c(AREA = NA_integer_,
PERIMETER = NA_integer_, ABIELASI_ = NA_integer_, ABIELASI_I = NA_integer_,
CODE = NA_integer_), class = "factor", .Label = c("constant",
"aggregate", "identity"))))
对于列表中的 1 个 shapefile，我可以通过以下操作轻松设置 crs：
st_crs(shapefiles[[1]]) <- 4326
如果我尝试使用此代码使用 lapply 或 purrr::map，则它不起作用。
lapply(myfiles, st_crs() <- 4326)
错误
Error in st_crs() <- 4326 : invalid (NULL) left side of assignment
我也尝试过以类似的方式使用 st_transform，但它也没有用。
我想做的是使用 st_crs(shapefiles[[1]]) <- 4326 之类的东西，但将其应用于列表中的每个元素（即 shapefile）。另外，我想避免使用 for 循环。我宁愿使用 apply 或 purrr 函数。
我们只需要 lapply 中的 lambda（匿名）函数来进行赋值，然后 return 原始对象
shapefiles2 <- lapply(shapefiles, function(x) {st_crs(x) <- 4326; x})
-输出
shapefiles2
$abieWEST.shp
Simple feature collection with 1 feature and 5 fields
Geometry type: POLYGON
Dimension: XY
Bounding box: xmin: -146.9409 ymin: 23.84307 xmax: -101.1053 ymax: 65.44589
Geodetic CRS: WGS 84
AREA PERIMETER ABIELASI_ ABIELASI_I CODE geometry
1 1 0 0 0 0 POLYGON ((-126.6233 63.8736...
$acerWEST.shp
Simple feature collection with 1 feature and 5 fields
Geometry type: POLYGON
Dimension: XY
Bounding box: xmin: -140.5147 ymin: 15.58627 xmax: -94.31022 ymax: 60.01365
Geodetic CRS: WGS 84
AREA PERIMETER ABIELASI_ ABIELASI_I CODE geometry
1 1 0 0 0 0 POLYGON ((-108.1462 15.5862...
或使用map
library(purrr)
map(shapefiles, ~ {
st_crs(.x) <- 4326
.x
})
另一种选择（如上面@Henrik 所建议的）是将 crs 作为 FUN 的可选参数（即 st_read）。
library(sf)
# Example (Not Run)
temp = list.files(path = "/data",
pattern = "*WEST.shp$",
full.names = TRUE)
myfiles = lapply(temp, st_read, crs = 4326)
输出
Reading layer `abieWEST' from data source
`/data/abieWEST.shp'
using driver `ESRI Shapefile'
Simple feature collection with 1 feature and 5 fields
Geometry type: POLYGON
Dimension: XY
Bounding box: xmin: -146.9409 ymin: 23.84307 xmax: -101.1053 ymax: 65.44589
Geodetic CRS: WGS 84
Reading layer `acerWEST' from data source
`/data/acerWEST.shp'
using driver `ESRI Shapefile'
Simple feature collection with 1 feature and 5 fields
Geometry type: POLYGON
Dimension: XY
Bounding box: xmin: -140.5147 ymin: 15.58627 xmax: -94.31022 ymax: 60.01365
Geodetic CRS: WGS 84